ok well i installed my modded jeep TB a while back and ever since then ive had a problem with it. on occasion it makes the car idle high, usually around the neighborhood of 2.5K...it doesnt do it all the time, but like when ive driven it around town for a little while. so this made me rule out a vacuum leak. when monitoring the TPS positon (via SAFC) when it does this it reads on average 8% throttle, but sometimes upwards of 20%. i had put a new TPS on the throttle body when i installed it. my last thought is the IAC solenoid is acting up, but i did swap out the pintles as required, but is it possible that maybe the pintle isnt completely making contact and not controlling the idle properly? sometimes this condition is corrected by cycling the ignition, but usually it just idles high. and then on occasion it just idles normal when a few seconds before it was in its high idle hijinx. another odd thought is maybe my install is flawed..lol to block off the factory idle hole in the intake manifold, i used an red blanking plug used in shipping engines in the hole. it fit really tight and seated up well, and i used thick gasket material when i cut my gasket for it, but maybe theres something about the heat in the mani and that gasket that makes it not seal right? any input would be greatly appreciated.

a friend of mine that ownes a jeep had same type of issue, all we did was re-seat the intake manifold with a new gasket and issue went away

hope that helps

I also have this issue with my Jeep TB.

Think that your spring could be too loose? I got another spring from an hardware store and it helped a ton. I did some searching and it talked about adjusting the IAC so that it's so many mm out. I cant talk too educated about this as I have yet to dive into it.

Let us know if you do find your problem.

Nick
97RS

is it normal for a SAFC to indicate around 5-6% throttle at closed throttle? even when the car is idling(properly) in my case? im just trying to narrow down any sources of my erratic idle. ive noticed that the SAFC isnt always accurate in throttle position.

Yes, it is normal. Your TB is never fully closed or else you wouldn't have any air for the motor to run at all.


Nick
97RS

i thought that was the purpose of the IAC solenoid...to create a controlled leak in the intake to allow enough air for the engine to idle? but it would stand to reason....

I never really thought about it like that, yet I don't know quite how the IAC works so I never questioned it.

I remember the first time I used a pocket logger I had the same question. It also reads like this on my buddy's safc.


For some reason I cant get my obd2 cable to register with any apps on my laptop.



Nick
97RS

Originally posted by DSMTalon
i thought that was the purpose of the IAC solenoid...to create a controlled leak in the intake to allow enough air for the engine to idle? but it would stand to reason....

It is. If your throttle body isnt closing all the way at idle then you have a massive vacuum leak. The IAC - Idle Air Controller is just that...

OK, understandable..
So why does the tps never show that it's completely closed?
Surely you've seen this.



Nick
97RS

ive noticed the same sort of issue with the SAFC...almost never does it say the throttle plate is completely closed...most of the time it reads .4% throttle or some other minuscule amount, but never 0. and like to say most of the time when i have my idle problem, it reads anywhere from 2-8% throttle. when i first installed the throttle body, i had actually put the TPS on wrong ( the little spade on the throttle on the wrong side of the sensor) so that it read like 12% throttle even with it completely closed, and it maxed out at like 2/3 pedal travel. so i corrected this, but the idle issue was still there. and more or less smooth application of throttle is non existent. but i figured this would be the case as it usually comes with the territory of a bigger tb than necessary.

It's been my experience with the Jeep TB's that the idle problem is usually spring related. I use two springs on my set-up. One on the shaft and one on the exterior.

can i get some pics of how you have those springs set up to compare to mine?